Physicists calculated that these mysterious particles will betray their location with heat. To prove it, they’ll need the most powerful telescopes in the cosmos.
WE’RE BATHING IN an uncertain universe. Astrophysicists generally accept that about 85 percent of all mass in the universe comes from exotic, still-hypothetical particles called dark matter. Our Milky Way galaxy, which appears as a bright flat disk, lives in a humongous sphere of the stuff—a halo, which gets especially dense toward the center. But dark matter’s very nature dictates that it’s elusive. It doesn’t interact with electromagnetic forces like light, and any potential clashes with matter are rare and hard to spot.
Physicists shrug off those odds. They’ve designed detectors on Earth made out of silicon chips, or liquid argon baths, to capture those interactions directly. They’ve looked at how dark matter may affect neutron stars. And they’re searching for it as it floats by other celestial bodies. “We know we have stars and planets, and they’re just peppered throughout the halo,” says Rebecca Leane, an astroparticle physicist with SLAC National Accelerator Laboratory. “Just moving through the halo, they can interact with the dark matter.”
For that reason, Leane is suggesting that we look for them in the Milky Way’s vast collection of exoplanets, or those outside our solar system.